Tappet



S. OLDBERG Feb. 23, 1960 TAPPET Filed Sept. 11, 1958 INVENTOR. -5/o/vY Owe/see BYZwM A NORA/5X5 United States Patent TAPPET Sidney Oldberg, Birmingham, Mich., assignor to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Application September 11, 1958, Serial No. 760,399

11 Claims. (Cl. 123-90) mitting mechanisms having hydraulic tappets reciprocable in bores of stationary guides, and where either the tappet or the bore of the guide has a surface which is convex axially of its length to render the tappet self-aligning, the

other surface being cylindrical.

Hydraulic tappets are supplied with lubricating oil under pressure from a supply port or passage in the tappet guide. In the case of self-aligning tappet mechanismsinvolving a convex surface, and where the oil supply and inlet means are near the top of the tappet, there may be a considerable loss of oil and a consequent drop in oil pressure.

. It is an object of this invention, therefore, to provide hydraulic tappet mechanisms of the type involving divergent surfaces between the tappet and guide bore with an effective sealing means to retain the supply of oil under pressure to the tappet.

It is also an object of this invention to provide improved tappets of the above-mentioned type in which the sealing means is in the form of a sealing ring carried in a groove in one of the divergent surfaces and slidably engaging the other surface. In those arrangements where the surface of the tappet itself is convex, as when the surface is hyperbolic, the sealing ring is advantageously retained or carried in an annular groove formed in the tappet. When the tappet is cylindrical and the convex surface is presented by the stationary guide, the sealing ring is preferably located in an annular groove in the bore surface and has sliding engagement with the tappet.

A further object of the invention is to provide novel Sealing means of the character describedwhich is placed between the tappet oil inlet groove or passage and an end of the tappet to prevent excessive oil loss from the space defined by the divergent surfaces of the tappet and the bore.

As another object, the invention aims to provide seal ing rings between the surfaces of hydraulic tappets and their guide bores and which rings may conveniently be of circular or rectangular cross-section, and of any suitable material such as rubber or metal.

Further objects and advantages of the invention, together with more specific details thereof, will appear from the following description taken in connection with the drawings forming a part of this specification, and in which:

Fig. 1 is a side view of a convex hydraulic tappet embodying this invention and seen in a cylindrical guide bore of an engine, with a portion of the latter shown in section, and

Fig. 2 is a side view, similar to Fig. l, but of a cylindrical tappet in a guide bore having a convex surface.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

A preferred form of the invention is shown in Fig. 1

and employs a hydraulictappet 10 of the self-aligning type having a peripheral surface '11 which is convex axially of the tappet length. One end of the tappet '10 is provided with a transverse cam engaging surface 12.

The other end 13 of the tappet 10 is adapted to receive ;a valve stem or push rod 14. The push rod 14 is shown here as partly broken away and is received by end 13 of tappet 10 to be seated within the tappet in a conventional manner.

A cam 15, carried by a camshaft '18 and having conventional base circle and ramp portions 1-6 and 17 respectively, is engaged by tappet end face 12.

The hydraulic tappet 10 is reciprocably mounted in a cylyindrical guide bore 19 formed in the stationary guide portion 20 of an internal combustion engine or the like. Rotation of camshaft 18 will result in reciprocation of the tappet 10 and the pushrod 14 seated therein. Because of the axial convexity of the tappet body surface 11, the tappet 10 is free to be angularly displaced with respect to the axis of the guide bore 19 within predetermined limits, thereby assuring more proper alignment and more full line contact between the cam 15 and cam engaging surface 12.

The hydraulic tappet 10 is further provided with an oil inlet port or passage 21 lying in an annular oil groove 29. (Opening into the bore 19 of the stationary guide 20 is an oil supply port or passage 22 which is in communication with an oil gallery 23 forming a part of the pressure lubricating system of the engine or the like.

Between the oil inlet port 21 and the end 13 of the tappet is disposed a sealing means in the form of a sealing ring or packing 27 which is retained or carried in an annular groove 28 formed in the surfacel-l of the tappet. The groove 28 has side walls which lie in planes transverse to the axis of the tappet 10 and the depth of the groove issuch that the ring 27 does not fully seat therein.

. The ring 27 slidably engages the surface 24 of the bore 19 and effects a seal between that surface and the surface 11 of the tappet 10. Because of the depth of the groove, the ring 27 is free to accommodate its position and maintain a sealing condition throughout the angular displacement of the tappet as it aligns itself in the manner mentioned above.

In this, the preferred form, the ring 27 is shown as being circular in section and is preferably made of metal, although rubber or other suitable flexible or resilient materials may be used. When formed from metal, the ring is advantageously provided with a clearance gap to allow The surface 24 of the cylindrical bore 19 and the con- A vex surface 11 of the tappet 10 are divergent in the vilarge space such as at 25 would result in an excessive loss of oil and a consequent drop in oil pressure.

Pursuant to this invention, and in accord with the preferred form described above, the sealing ring 27 prevents the loss of oil from the space 25 and thereby maintains an adequate supply of oil under sufficient pressure to enable the hydraulic tappet to carry out its lash eliminating or valve take up function.

A modified form of the tappet mechanism is illustrated in Fig. 2 which differs from that of Fig. 1 in that a peripheral surface 31 of axial convexity is provided on the guide bore instead of on the body of the tappet, and wherein the peripheral surface 32 of the tappet is cylindrical. The sealing ring 33 in the modified form is quadrangular or rectangular in section and is received in an annular groove 34. Ring 33 has sliding engagement with the cylindrical surface 32 of the tappet and effects a seal against the loss of oil from the annular space 25 defined by the divergent surfaces 31 and 32. This structure is otherwise comparable to that of Fig. 1 in its function and details of construction.

From the foregoing description and the accompanying drawings it can readily be seen that this invention provides an improved hydraulic tappet mechanism which, by reason of its novel arrangement, effectively uses divergent surfaces in a guiding relation for self-alignment of the tappet without excessive loss of oil or drop in oil pressure. Additionally, it can be seen that a tappet and guide therefore have been combined in a manner achieving the above-recited objects, and resulting in a mechanism having advantages not heretofore attainable together in a single tappet or motion transmitting mechanism.

Although the improved tappets of this invention have been described herein in some detail, and with reference to several specific embodiments, it is understood that the invention is not to be regarded as being limited correspondingly in scope, but includes all changes and modifications coming within the terms of the claims hereof.

Having described my invention, I claim:

1. A motion transmitting mechanism comprising, a stationary member having a supply passage for lubricating fluid and also having a guideway presenting a peripheral surface, a tappet member reciprocable in said guideway and adapted to receive fluid from said passage, said tappet member having an axially extending peripheral surface in guiding cooperation with the peripheral surface of said guideway, one of said surfaces being cylindrical and the other being axially convex, and sealing means between said surfaces for confining said fluid.

2. A motion transmitting mechanism comprising, a reciprocable tappet member having an axially extending peripheral surface, a stationary guide member having a bore presenting a peripheral surface, said tappet member being arranged for reciprocation in said bore with said surfaces in guiding relation, one of said surfaces being cylindrical and one of said surfaces being convex axially of its length whereby said surfaces are divergent from the mid portions thereof toward the end portions thereof, said tappet member and said guide member having ports in communication with the space between said divergent surfaces, and sealing means between said surfaces for retaining the flow of fluid under pressure through said ports to said tappet member.

3. A motion transmitting mechanism comprising, a hydraulic tappet member having an axially extending peripheral surface and having a hydraulic fluid inlet port, a stationary guide member having a bore defined by a peripheral surface and having a hydraulic fluid supply port, said tappet member being arranged for reciprocation in said bore with said surfaces in guiding relation, one of said surfaces being cylindrical and one being convex axially of its length whereby said surfaces are divergent from the mid portions thereof toward the end portions thereof and define a space in communication with said ports, and a sealing ring mounted on the member having said convex surface and engaging said cylindrical surface for confining the flow of hydraulic fluid under pressure from said supply port to said inlet port.

4. A hydraulic tappet for use in a cylindrical guide bore, said tappet having a peripheral surface which is convex axially of its length and also having an inlet opening in said surface between an end and the center of said tappet, and a sealing ring mounted on said tappet at a point between said end and said inlet passage, said sealing ring being in sliding engagement with the wall of said cylindrical guide 'bore.

5. In the combination of a hydraulic tappet and a stationary guide, a hydraulic tappet having a cylindrical surface and having an oil inlet passage opening in said surface between one end and the center of said tappet, said stationary guide having a bore defined by an axially convex surface, said tappet being reciprocably received in said bore whereby said surfaces are divergent axially towards the ends thereof defining a crevice between said surfaces, said stationary guide having an oil supply passage, said crevice being in communication with said passage, an annular groove defined in said convex surface, and a sealing ring received in said groove and engaging said cylindrical surface between said inlet passage and said end of said tappet.

6. The mechanism of claim 3 and wherein said sealing ring is circular in cross-section.

7. The mechanism of claim 3 and wherein said sealing ring is quadrangular in section.

8. A hydraulic tappet for use in a cylindrical guide bore, said tappet having a cam engageable end and a push rod engageable end and having a peripheral surface which is convex axially of its length, said tappet having an .oil inlet passage between the push rod engageable end and the center of said tappet, said tappet having an annular groove between said inlet passage and the lastmentioned end and defined by side walls extending transversely of the axis of said tappet, and a sealing ring disposed in said groove and adapted to engage said cylindrical guide to retain oil under pressure supplied from said cylindrical guide.

9. The tappet of claim 8 wherein said ringhas a clearance gap.

10. The tappet of claim 8 wherein said ring has a clearance gap and is circular in cross-section.

11. The tappet of claim 8 and wherein the surface convex axially of its length is defined by a portion of a hyperbola.

References Cited in the file of this patent UNITED STATES PATENTS 2,570,853 Pierce Oct. 9, 1951 2,749,890 Oldberg June 12, 1956 2,756,733 Meile July 31, 1956 2,761,435 Oldberg Sept. 4, 1956 

